Fireproof stair.



D. A. ANDERSON.

FIREPROOF STAIR. APPLICATION FILED EBB. 27, 1911.

Patented Nov. 11

In ian o A Anderson. ?35

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UNITED srarns PATENT orn on j DAVID A. sn'nnnson, or omoaeo, 'InLrnors.

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Specification of Letters Patent.

Application filed February 27, 1911.' Serial No. 611,015. i 2

To a l whom it may concern:

Be it known that I, DAVID A. ANDERSON,

a citizen of theUnited- States, residing at ferent stages of completion; Fig. 2 is a.

transverse section of a single step; and Fig. 3 is a transverse section of a step embodying my invention in' slightly modified form.

In the drawings, 5 indicates a stringer, preferably of metal, affording horizontal step-carrying ledges, 6, preferably formed of angle irons, suitably secured to the stringers as by bolts or rivets 7 8-8 indicate sheet metal foundation members, each of which comprises, in part, a horizontally disposed tread foundation or bed-plate that its end resting upon the ledges 6, and secured thereto by bolts'10. Each said plate 9 has its forward edge bent upward to form, a nosing 11, and then inward to form a lip 11', and in some instances I prefer that the nosing shall have a series of apertures 12in its lip, through which the cement or other material of the tread may key to form an anti-slip nose.

The rear edge of thebed plate 9 is bentupwardly to form a rear w'all'13, gener ally opposing the nosingyll, and as shown in Figs. 1 and 2, where a closed stairway is to.be provided,- this rear Wall may be carried upward to form a riser 14, having'its edge turned back to form a flange as at 15, to be secured by bolts 16 to the bed member next aboye, just back of its nosing, or as shown in Fig. 3, where an open stairway is to .be provided without risers,

the rear Wall 13 may have its edge turned forwardly'in a lip, as at 14, at the same elevation as the inturned lip of the nosing. To provide the tread proper of the stair,

. each member; or bed plate is filled with concrete, cement, or like plastic material, in-

dicated at 17, to the level" of the nosing lip 11.. but I prefer that the concrete body 17 shall be reinforced by metal rein-forcing devices which also serve effectually to unite and brace the nosing wall 11' and the rearwall 13 of the foundatiom Thus, specifically, I provide transverse brace bars 18, each provided witha foot 19 at its ends," and said feet, .I secure as by rivets. 20 respectively to the nosing wall 11 and the rear wall 13 of the; foundation member.- These brace bars 18 serve also as restswand spacers for, longitudinal reinforcing rods 22' and-tothis end preferably the upper edge of each brace 18 is notched-as at 23, for thereception of the appropriate rods 22 whichextend from end to end ofthe step. The arrangement preferred locates these rods 22- at about the vertical center ofthe plastic mass 17 forming the tread proper, and obviously the rods and transverse braces serve to distribute throughout each step. strains imposed upon any point of the tread Stl'uOtfl1'C,,:-1l1(l to reinforce the, plastic against cracking, disintegration, or displaceme; Additionally, the transverse bracing maintains the sheet metal foundation members against bending or lateral displacement of its vertical walls and tendsto prevent, bending or buckling of the horizontal web 9 of each said bed portion, by throwing a portion of thestrains upon the nosing and rearwallQ Where the apertured nosing is com ployed as shown in Fig. 1, the plastic mass 17 fills the apertures as at 17, and is, smoothed off flush with or slightly pro truding from the metal to form an anti-slip edge for the tread. v

WVhile I have herein described in some detail a. particular embodiment of my invention, it will be apparent tothose skilled in the. art that many changes might be made in detail Without departure from the spirit of the invention and within the scope of the appended claims.

What I claim is: p 1. In a stair structure, the combination with a stringer providing horizontal ledges, sheet metal foundation memberscarried by said ledges providing in an integral structure a tread-bed, a nosing upturned from one edge of said tread-bed, a riser upturned from the opposite edge of said treadbed, and a rearwardly extending flange turned back from the free edge of the riser; means, below the edge of the nosing and Patentetl Nov. 1 1, 1913 .above the level of the tread bed, secured'to and connecting said nosing and riser for mutual strengthening and bracing effect upon said nosing and riser; means securing the rearwardly turned flange of each d member to the under side of the treadibe by said bed and, through said rods braces, by nosing and riser.

tween the nosing and rear wall connected portion of the. member next above, and? body of plastic material constituting the tread proper and confined by the nosing and 1:0 riser and reinforced by the bracing means of the nosing and riser.

2. A stair structure comprising foundation members each providing a tread bed having a front nosing and a rear wall bentupwardly therefrom, transverse bracing connections extending between and securely attached to said nosing and rear walls at points above the bends between the bed and the nosing and riser respectively, said nosing and riser being provided at such points with means for such attachment, and a plastic tread body embedding said braces for partial support by said vertical nosing I and riser.

3. In a stair, a step comprising a sheet v metal foundation formed to provide a tread bed, a front nosing, and a rear wall opposing'fsaid nosing each bent upwardly from the respective edge of the tread bed,

3P0 transverse braces connecting said nosing and the rear wall to maintain them in vertical position by mutual support, longitudinal reinforcing means, and a plastic tread body between said vertically maintained 3 5 nosing and rear wall and embedding said braces and longitudinal reinforcing means to provide one of a plurality of interchangeable units for stair construction.

4. In a stair, a step comprising a sheet :10 metal foundation formed to provide a tread ,bed, a front nosing, and a rear wall opposing said nosing, transverse braces connect-- ing said nosing and the rear wall for mutual strengthening of said vertical nosing l and wall, longitudinal reinforcing rods carried by the transverse braces and, through the agency of said braces, by said vertical walls and a plastic tread body bounded by said bed, nosing and riser and embedding the said braces and rods for support jointly to the nosing below its free upper edge, said nosing being perforated along its upper edge, and a tread body of plastic material embedding said bracing means and filling said perforationsv whereby the nosing is braced by the embedded bracing means below its upper edge, and at its upper edge is intimately associated with the plastic material which is reinforced by, and which embeds, said bracing means, to form a complete interchangeable stair unit.

6. In a stair, the combination with stepcarrying ledges, of a plurality of step structures, each comprising, in a singlepiece sheet-metal structure a horizontal bed plate resting upon said step-carrying ledges, a nosing bent vertically upward from the forward edge of the bed plate, a riser bent vertically upward from the rear edge of the bed plate, and a horizontal flange at the upper edge of the riser for connection to the under side of the bed plate of the step next above; a bracing structure extending between and secured to said nosing and riser whereby said vertical and horizontal portions of the sheet metal foundation member are braced against displacementor buckling, and whereby each foundation structure and its bracing may be completely assembled be? fore erection; a body of plastic material filling the space between said nosing and the opposite portion of the riser; and reinforcing members lying centrally embedded in said plastic body and carried by said bracing structure, whereby the strains imposed upon said plastic body are borne in part by the vertical nosing and riser portions of the metal step structure. 1

In testimony whereof I hereunto set my handin the presence of two witnesses.

DAVID' A. ANDERSON. In the presence of- MARY F. ALLEN, W. LINN ALLEN. 

